1. Field of the Invention
This invention relates to augers for agricultural mixers, specifically vertical type feed mixers.
2. Discussion of Background Art
Agricultural mixers are used for mixing hay and silage together with other nutrients including animal feed supplements and grains. These feed materials are then discharged and fed to various livestock such as cattle and dairy cows. Sometimes the mixing of such feed includes depositing a whole round or square bale of hay into the mixer. The mixer then cuts and processes the bale into the desired consistency before and during the mixing of the other feed nutrients.
In conventional mixers, there are many different configurations including horizontal augers, reel type arrangements, and vertical augers. In the vertical auger type mixers, the auger designs are generally similar from mixer to mixer. The auger for a vertical type mixer generally consists of a center core on a vertical axis, with helical auger flighting wrapped around this core. The auger flighting has an overall conical appearance, being wider at the base and narrower at the top. The flighting can also consist of a series of paddles arranged in a spiral pattern. Knives are added to the flighting to help cut and process the feed materials. The wide front edge of the flighting at the bottom of the mixer is made to travel close to the flat floor of the mixer, scooping or peeling the material upwards onto the flighting.
In addition to the leading edge at the base of the auger, the augers sometimes include additional bars, paddles, or sections of flighting around the base. These paddles, sometimes called “kickers” help move the material being mixed, urging the material in a particular direction. A conventional kicker generally includes a relatively flat bar or plate which is lower at the front edge than at the rear edge, and can be mounted by itself or in combination with the lighting. The quantity, size, and orientation of the kickers varies depending on the type of materials, type of mixing action, mixing speed, or horsepower consumption desired. These kickers also sometimes include a hardened bar at their leading edge to increase the durability of the auger.
The general principle of a vertical mixer auger is to sweep materials onto the front edge of the lower flighting section, where it is elevated upwards, sliding on top of the flighting sections, to the trailing edge of the upper lighting. As the feed material is carried upwards by the auger flighting, a void is created between the auger flighting and the sidewall of the mixer. The material from above falls downward into this void, causing a continuous boiling action of the material inside the mixer. After mixing is complete, a discharge door is opened and the materials are pushed out of the discharge opening onto a discharge chute or conveyor. If there are no kickers on the auger, then the front edge of the helical flighting helps to urge the feed materials out the door once per auger revolution. If a kicker is utilized, it would normally be positioned on the opposite side of the auger, thus urging feed materials towards the discharge a second time per auger revolution. Additional kickers spaced evenly around the circumference of the auger can be used to attain a smoother flow of feed materials through the discharge opening.
A “straight kicker” is defined as a kicker with a leading edge that forms an angle as seen from above approximately 90° with a plane of the discharge opening as the straight kicker passes by the centerline of the discharge opening during rotation of the auger. When a “straight kicker” is used, feed is urged toward the discharge opening as the outer portion of the kicker approaches the first edge of the discharge opening. As the outer portion of the straight kicker reaches the discharge opening centerline, it stops urging the feed material towards the discharge opening, and begins pulling the feed back into the mixer. Thus, the feed material urged by a straight kicker is mainly discharged between the first edge of the discharge opening and the discharge opening centerline and then is pulled back into the mixer. Therefore, discharge efficiency is reduced.
The vertical mixer also relies on the pressure of the material in the top portion of the machine to help push the materials out the door. Especially in the case of relatively lightweight materials, the discharge area can become clogged or restricted. In these cases, the user must wait until sufficient pressure is built up by the auger or kickers to force the materials out. Conventional augers and kickers have had little success in resolving this particular clogging problem, as the kickers are typically designed with a straight edge radiating from the auger core to facilitate a rotary action, as opposed to an outward action toward the door opening.
Thus, one disadvantage of straight auger kickers is that lightweight materials can clog during attempted discharge from the discharge opening. Another disadvantage of having straight kickers is that feed materials are urged towards the discharge opening only during the first half of the rotation past the discharge opening, after which materials are pulled back inward. Yet another disadvantage of having straight kickers is that the feed materials tend to pulse as they are discharged through the discharge opening, rather than discharge with a more desirable steady flow.